1. Blow balloons in a bottle?
Thinking: Why doesn't the balloon become smaller when it is blown in a bottle?
Materials: large glass bottle, two red and green straws, a balloon and a pump.
Operation:
1. Punch two holes in the bottle cap with a screwdriver in advance, and insert two straws in the holes: red and green.
Tie a balloon on the red straw.
3. Cover the bottle cap on the bottle mouth.
4. Inflate the balloon at the red straw with an air pump.
5. Loosen the red straw and the balloon will become smaller immediately.
6. Use the air pump, and then click the red straw to expand the balloon.
7. Quickly pinch the two nozzles of the red straw and the green straw.
8, let go of the red straw mouth, the balloon has not become smaller.
Explanation: Loosen the red straw, and the balloon will begin to contract due to the contraction of its rubber film. But after the balloon is deflated, the air volume in other parts of the bottle becomes larger and the green tube is closed. In this way, the air pressure in the bottle will be reduced-even lower than that in the balloon. At this time, the balloon will not continue to shrink.
Second, the cup that can catch the balloon?
Thinking: Is it right to gently invert a small cup on the spherical surface of the balloon and then suck it up?
Materials: 1 ~ 2 balloons, 1 ~ 2 plastic cups, 1 thermos, a little hot water.
Process:
1、? Blow up the balloon and fasten it.
2、? Pour hot water (about 70℃) into about half a cup.
3、? After the hot water stays in the cup for 20 seconds, pour out the water.
4、? Immediately fasten the cup mouth tightly on the balloon.
5? Gently lift the cup with a balloon?
Note: 1. If the cup falls directly on the balloon, it is impossible to suck it up. 2. The cup treated with hot water can suck up the balloon, because the air in the cup is gradually cooled and the pressure is reduced.
Third, the cup that will absorb water?
Thinking: Cover the burning candle with glass. What happens in the glass when the candle goes out?
Materials: 1 glass (higher than candle), 1 candle, 1 tablet, 1 lighter and some water.
Operation:
1. Light the candle and fix the candle with a few drops of wax oil in the center of the plate.
2. Fill the plate with water about 1 cm high.
3、? Invert the candle with a glass.
4. Observe the candle burning and the change of water level in the dish.
Explanation: 1 After the air (oxygen) in the glass is consumed, the candle flame goes out. When the candle goes out, the water level in the cup will gradually rise.
Fourth, the bottle that can eat eggs?
Thinking: Why can eggs enter from bottles smaller than themselves?
Materials: 1 boiled egg, 1 narrow-mouth bottle, a few sheets of paper, 1 box of matches.
Operation:
1, shell the eggs.
2. Tear the paper into strips.
3. Light the note and put it in the bottle.
As soon as the fire goes out, buckle the egg to the bottle mouth and take your hand away immediately.
Explanation: 1 The bottle was hot when the paper first burned. 2. After the egg is buckled in the bottle mouth, the temperature in the bottle gradually decreases, the pressure inside the bottle becomes smaller, and the pressure outside the bottle becomes larger, so that the egg will be squeezed into the bottle.
5. The bottle is flat?
Thinking: Can you deflate plastic bottles without hands?
Ingredients: 2 cups, 1 cup of warm water, 1 bottle of mineral water.
Operation:
1, put warm water in the bottle and touch the bottle with your hand. Do you feel hot?
2. Pour the warm water out of the bottle and close the bottle cap quickly.
3. Watch the bottle deflate slowly.
Explanation: 1 Heat the air in the bottle to reduce its pressure. 2.？ Because the air outside the bottle is under greater pressure than the air inside the bottle, the bottle is crushed.
Extended data:
Physics experiment teaching is an important form and method of physics teaching. Generally, it is divided into demonstration experiment, small experiment in class (experiment while talking), student group experiment and extracurricular experiment. Demonstration experiment is a performance demonstration experiment with teachers as the main operators.
In-class experiment is a small experiment operated by students in the process of classroom teaching. Student grouping experiment is a process in which students use instruments, observe and measure, obtain data, analyze and process data, and summarize conclusions, including confirmatory experiments and exploratory experiments.
References:
Baidu Encyclopedia: Physics Experiment Teaching